An agricultural row crop planter is a machine built for precisely distributing seed into the ground. The row crop planter generally includes a horizontal toolbar fixed to a hitch assembly for towing behind a tractor. Row units are mounted to the toolbar. In different configurations, seed may be stored at individual hoppers on each row unit, or it may be maintained in a central hopper and delivered to the row units on an as needed basis. The row units include ground-working tools for opening and closing a seed furrow, and a seed metering system for distributing seed to the seed furrow.
In its most basic form, the seed meter includes a housing and a seed disc. The housing is constructed such that it creates a reservoir to hold a seed pool. The seed pool may also be in a separate structure. The seed disc resides within the housing and rotates about a generally horizontal central axis. As the seed disc rotates, it passes through the seed pool where it picks up individual seeds. The seeds are subsequently dispensed into a seed chute where they drop into the seed furrow.
Seed spacing in the seed furrow is controlled by varying the rotational speed of the seed disc. Most commonly, seed disc rotation is driven by connection to a common driveshaft. The driveshaft runs horizontally along the length of the toolbar to connect to each row unit, and is driven by a single motor or a ground contact wheel. In this configuration, the planting rate can be adjusted for all row units uniformly by adjusting the rotational speed of the common drive shaft. This can be a tedious task, and an operator is unlikely to adjust the gear ratio as often as necessary to maximize yields. Generally, an optimal overall rate for a given acreage will be selected prior to planting and will be maintained at that rate regardless of soil conditions. Whether using a mechanical, air, or vacuum style seed disc, the seed disc is installed inside of the seed meter using independent fasteners and requires the use of tools to facilitate changing the disc. For example, if a farmer uses the same planter to plant corn and soybeans, he would use a different disc for the respective seed types. With planters continuing to grow in size, and more row units being added, the task of changing seed discs using independent fasteners and tools adds unnecessary burden to changing out seed discs.
More recently, planters have been designed to provide for independent driving of each of the seed discs in each seed meter. The meters include a motor, such as an electric motor, that is attached to the meter. For example, a DC brushless motor can be utilized, which includes an output shaft. The output shaft extends from the motor and into the meter such that a portion of the shaft is operatively connected to the seed disc. Therefore, the motor will operate to rotate the seed disc.
However, when electrically driving seed meters, the electric motor must either directly drive the seed disc via a hub or other connection method. The motor being used is placed axially and is detached from the seed disc, which increases the axial width of the seed meter. This setup makes motor removal and installation difficult. Another method is to transfer power to the seed disc through gears, belts, or other power-transmitting means, which allows the motor to be placed in a more suitable location and making it easier to service. These attempts have had the seed disc divorced from the drive motor, with power being transferred through gears, belts, etc., or the disc had to be directly attached to the output shaft of the motor, which would cause the system to have an increase in axial length since gear reduction would have to be done in the motor to slow the speed down to sufficient levels.
Therefore, there is a need in the art for a seed meter including a seed disc that has a smaller width than that of a seed meter being driven by an external, electric drive motor. There is also a need in the art for a meter that includes a modular-type disc driving motor that can be quickly attached to different seed discs used to distribute and plant different types of seed.